Presentation-quality maps with Google Earth Engine and R

Adding satellite imagery to your presentation? It’s easy to go overboard on data resolution, especially when our motivations are crisp, beautiful images. I like to process raw imagery, because I can choose data filtering techniques, temporal windows, etc. But, when Landsat data has a 30-m pixel, an image from a large region of interest may be 100’s of MB or even reach into the GB realm. How can we cut down on data volume but still get some beautiful satellite imagery for a presentation?

In this tutorial, we will walk through the process of accessing, filtering, and downloading imagery using Google Earth Engine, and then plot and save maps using R and the tidyverse.

The workflow should include:

• Identify region of interest
• Create masks to remove clouds and water
• Select data within a timeframe of interest
• Apply masks
• Calculate target pixel values
• Export image

And finally you should end up with an image that looks something like the one below. Recall that a 4k display has 3840x2160 pixels; there’s no reason to shoot for more detail than that if this plot is for a presentation. A 7“x7” image with 300 pixels per inch will end up being 2100x2100 pixels, a nice size for a half-slide image. Saved as a jpg, the final file size comes out to about 816kB.

Happy mapping!